[PATCH] c++: Avoid duplicate diagnostic calling unavailable function [PR109177]

[PATCH] c++: Avoid duplicate diagnostic calling unavailable function [PR109177]

[Alex Coplan]

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Hi,

As the PR shows, we currently emit duplicate diagnostics for calls to
functions marked with __attribute__((unavailable)). This patch fixes
that.

I'm not sure whether it's considered acceptable to add the include of
decl.h to call.cc (in order to get at deprecated_state). It would be
useful to get some feedback on that.

Bootstrapped/regtested on aarch64-linux-gnu, OK for trunk?

Thanks,
Alex

gcc/cp/ChangeLog:

	PR c++/109177
	* call.cc (build_over_call): Use make_temp_override to suppress
	both unavailable and deprecated warnings when calling
	build_addr_func.

gcc/testsuite/ChangeLog:

	PR c++/109177
	* g++.dg/ext/pr109177.C: New test.

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diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index c52a09b9be2..d5e8ccc07d3 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -41,6 +41,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "internal-fn.h"
 #include "stringpool.h"
 #include "attribs.h"
+#include "decl.h"
 #include "gcc-rich-location.h"
 
 /* The various kinds of conversion.  */
@@ -10413,10 +10414,11 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
     }
   else
     {
-      /* If FN is marked deprecated, then we've already issued a deprecated-use
-	 warning from mark_used above, so avoid redundantly issuing another one
-	 from build_addr_func.  */
-      warning_sentinel w (warn_deprecated_decl);
+      /* If FN is marked deprecated or unavailable, then we've already
+	 issued a diagnostic from mark_used above, so avoid redundantly
+	 issuing another one from build_addr_func.  */
+      auto w = make_temp_override (deprecated_state,
+				   UNAVAILABLE_DEPRECATED_SUPPRESS);
 
       fn = build_addr_func (fn, complain);
       if (fn == error_mark_node)
diff --git a/gcc/testsuite/g++.dg/ext/pr109177.C b/gcc/testsuite/g++.dg/ext/pr109177.C
new file mode 100644
index 00000000000..cc322f650af
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/pr109177.C
@@ -0,0 +1,6 @@
+// { dg-do compile }
+void foo() __attribute__((unavailable));
+void bar () {
+  foo (); // { dg-bogus "is unavailable.*is unavailable" }
+  // { dg-error "is unavailable" "" { target *-*-* } .-1 }
+}

Re: [PATCH] c++: Avoid duplicate diagnostic calling unavailable function [PR109177]

[Jason Merrill]

On 3/22/23 07:32, Alex Coplan wrote:
> Hi,
> 
> As the PR shows, we currently emit duplicate diagnostics for calls to
> functions marked with __attribute__((unavailable)). This patch fixes
> that.
> 
> I'm not sure whether it's considered acceptable to add the include of
> decl.h to call.cc (in order to get at deprecated_state). It would be
> useful to get some feedback on that.

That's fine.

> Bootstrapped/regtested on aarch64-linux-gnu, OK for trunk?

OK.

> gcc/cp/ChangeLog:
> 
> 	PR c++/109177
> 	* call.cc (build_over_call): Use make_temp_override to suppress
> 	both unavailable and deprecated warnings when calling
> 	build_addr_func.
> 
> gcc/testsuite/ChangeLog:
> 
> 	PR c++/109177
> 	* g++.dg/ext/pr109177.C: New test.